Systems with more degrees of freedom than restrictions and goals can be operated in many different ways while still achieving the same stated goals. A typical example is a car which can be driven between two points through different routes, at different speeds, in different gears and using the breaks differently.
If how these systems perform on non-stated goals is analyzed, usually room for improvement is found. For instance, most cars are neither operated using the minimum possible amount of gas, nor wearing them as little as possible, nor achieving the minimum transit time legally and safely possible.
Once an optimal system is designed for a given environment, it is often the case where the environment itself changes the system no longer optimizes its originally designed function.
Additional difficulties with existing systems may be appreciated in view of the description below.